Test devices for dry chemical analysis of fluids typically include one or more reagent matrix areas retained in a holder or attached to a substrate. These reagent matrix areas detect chemical components of sample liquids by a color reaction formed when the reagent contacts the liquid sample.
Test devices or strips for dry chemical analysis of fluids are well established in the art and used in agriculture, industry and medicine. For these applications it is desirable that the test devices be simple and inexpensive to produce.
Such devices are described in U.S. Pat. Nos. 4,774,054, 3,798,004 and 4,647,430 in which multilayer filters are glued to a substrate. The use of glue, however, can have a detrimental effect on the reagents used and their storage life as well as complicating the assembly of the device.
The use of a filter holder in a test device, such as in U.S. Pat. No. 4,912,034, eliminates the need for the use of glue in the test device, but also increases the device's complexity.
A simplified filter holder test device is described in U.S. Pat. No. 2,785,057, however this device employs a perforated disk filter retaining member abutting an absorbent layer which would not be suitable for chemical analysis of whole blood samples.
Accordingly there is a need in the art for a simple device for dry chemical analysis of fluids which can be used for chemical analysis of whole blood samples. The present invention fulfills this need and provides related advantages.